1. Field of the Invention
The present invention relates to an image forming apparatus, an image forming method and a program thereof, which can prevent a printed document from being illegally copied.
2. Description of the Related Art
In order to prevent a printed document from being illegally copied, the following method is proposed. In creating the document, a copy condition whether or not the document is in a state of “copy prohibition” is embedded within the document in the form of image data and the document is printed out. On the other hand, in copying the document, a copying machine detects the copy condition from the printed document and controls a copying operation according to the copy condition (i.e., an execution of the copying operation and a stop of the copying operation).
For example, Japanese Patent Application Laid-open No. 2002-305646 discusses a method in which a copying machine includes a unit for detecting a specific symbol (e.g., a two-dimensional code) and a secrecy level from the document to be copied, and in a case where the specific symbol is detected, the copying machine further detects the secrecy level to control the copying operation according to the secrecy level. According to this method, only by judging whether or not the specific symbol is included in the document to be copied, a determination can be made as to whether or not control of the copying operation is necessary with respect to the document.
On the other hand, there also is a method in which the image forming apparatus preliminary stores information as to a key word and image pattern that are used in restricting the copying and compares the information with information of all the documents input, thereby restricting the copying.
However, with the method of Japanese Patent Application Laid-open No. 2002-305646, copying of the print product, which contains no two-dimensional code, cannot be restricted. In a case where information as to the keyword and the image pattern that restrict the copying is stored, and the information is compared with the information of all the documents input, if the key word and the image pattern which are to be preliminary stored in the print product to be copied are not included in the print product, the copying cannot be restricted. As described above, in either one of the methods, only a specific print product could be restricted from being copied, so that there was a problem that the print product of which copying had to be prohibited was illegally copied.